同一列上具有多个外键的实体框架核心

Question

我有 3 个表与同一个 TransactionLog.DocumentId 列有关系。 我用 DocumentTypeId 区分外键：

1 - 发票， 2 - 借记单， 3 - CreditNote

我为实体搭建脚手架：

public partial class TransactionLog
{
    public int TransactionLogId { get; set; }
    public int? DocumentId { get; set; }
    public int? DocumentTypeId { get; set; }
    public decimal? Amount { get; set; }

    public CreditNote CreditNote { get; set; }
    public Invoice Invoice { get; set; }
    public DebitNote DebitNote { get; set; }
}

public partial class Invoice
{
    public Invoice()
    {
        TransactionLog = new HashSet<TransactionLog>();
    }

    public int InvoiceId { get; set; }
    public string InvoiceNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> TransactionLog { get; set; }
}

public partial class DebitNote
{
    public DebitNote()
    {
        TransactionLog = new HashSet<TransactionLog>();
    }

    public int DebitNoteId { get; set; }
    public string DebitNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> TransactionLog { get; set; }
}

public partial class CreditNote
{
    public CreditNote()
    {
        TransactionLog = new HashSet<TransactionLog>();
    }

    public int CreditNoteId { get; set; }
    public string CreditNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> TransactionLog { get; set; }
}

我想在 Invoice、DebitNote 和 CreditNote 表中分别插入 1 条记录，并在 TransactionLog 中为每笔交易插入 3 条记录。

这是我的代码：

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {

        modelBuilder.Entity<CreditNote>(entity =>
        {
            entity.Property(e => e.Amount).HasColumnType("decimal(18, 4)");

            entity.Property(e => e.CreditNoteNumber)
                .HasMaxLength(50)
                .IsUnicode(false);
        });

        modelBuilder.Entity<DebitNote>(entity =>
        {
            entity.Property(e => e.Amount).HasColumnType("decimal(18, 4)");

            entity.Property(e => e.DebitNoteNumber)
                .HasMaxLength(50)
                .IsUnicode(false);
        });

        modelBuilder.Entity<Invoice>(entity =>
        {
            entity.Property(e => e.Amount).HasColumnType("decimal(18, 4)");

            entity.Property(e => e.InvoiceNumber)
                .HasMaxLength(50)
                .IsUnicode(false);
        });

        modelBuilder.Entity<TransactionLog>(entity =>
        {
            entity.Property(e => e.Amount).HasColumnType("decimal(18, 4)");

            entity.HasOne(d => d.CreditNote)
                .WithMany(p => p.TransactionLog)
                .HasForeignKey(d => d.DocumentId)
                .HasConstraintName("FK_TransactionLog_CreditNote");

            entity.HasOne(d => d.DebitNote)
                .WithMany(p => p.TransactionLog)
                .HasForeignKey(d => d.DocumentId)
                .HasConstraintName("FK_TransactionLog_DebitNote");

            entity.HasOne(d => d.Invoice)
                .WithMany(p => p.TransactionLog)
                .HasForeignKey(d => d.DocumentId)
                .HasConstraintName("FK_TransactionLog_Invoice");
        });
    }

但是，DocumentId 没有保存正确的 InvoiceId、CreditNoteId、DebitNoteId。我用 SQL Profiler 检查，它总是会得到 3 个插入的第一个 scope_identity()，在我的例子中是 CreditNoteid。

知道如何从 Invoice、CreditNote 和 DebitNote 中获取正确的 ID 吗？ 或者我不应该在这种情况下使用关系。 如果不是，将事务记录到日志中的最佳做法是什么？

Answer 1

在您的DbContext 中添加以下配置，然后添加迁移并相应地更新数据库。

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<Invoice>().HasMany(i => i.TransactionLog).WithOne(tl => tl.Invoice).HasForeignKey(tl => tl.DocumentId);
    modelBuilder.Entity<DebitNote>().HasMany(dn => dn.TransactionLog).WithOne(tl => tl.DebitNote).HasForeignKey(tl => tl.DocumentId);
    modelBuilder.Entity<CreditNote>().HasMany(cn => cn.TransactionLog).WithOne(tl => tl.CreditNote).HasForeignKey(tl => tl.DocumentId);
}

Answer 2

我认为也许外键的方向是错误的。

作为您的表定义，TransactionLog.DocumentId 的值必须同时存在于三个表中（InvoiceCreditNoteDebitNote）。所以，如果只插入其中两个，可能会有异常。

我想你真的希望表定义是这样的。 我删除了TransactionLog.DocumentId列，并将三个表的PK中的FK添加到TransactionLog.TransactionLogId。

实体：

public partial class TransactionLog
{
    public int TransactionLogId { get; set; }
    public Nullable<int> DocumentTypeId { get; set; }
    public Nullable<decimal> Amount { get; set; }

    public virtual CreditNote CreditNote { get; set; }
    public virtual DebitNote DebitNote { get; set; }
    public virtual Invoice Invoice { get; set; }
}

public partial class Invoice
{
    public int InvoiceId { get; set; }
    public string InvoiceNumber { get; set; }
    public decimal Amount { get; set; }

    public virtual TransactionLog TransactionLog { get; set; }
}

public partial class CreditNote
{
    public int CreditNoteId { get; set; }
    public string CreditNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public virtual TransactionLog TransactionLog { get; set; }
}

public partial class DebitNote
{
    public int DebitNoteId { get; set; }
    public string DebitNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public virtual TransactionLog TransactionLog { get; set; }
}

代码：

Invoice invoice = new Invoice() { InvoiceNumber = "Inv0100", Amount = 66m };
TransactionLog invoiceLog = new TransactionLog() { Amount = invoice.Amount, DocumentTypeId = 1 };
invoice.TransactionLog = invoiceLog;
_context.Invoices.Add(invoice);

CreditNote creditNote = new CreditNote() { CreditNoteNumber = "DN003", Amount = 99.99m };
TransactionLog creditNoteLog = new TransactionLog() { Amount = creditNote.Amount, DocumentTypeId = 2 };
creditNote.TransactionLog = creditNoteLog;
_context.CreditNotes.Add(creditNote);

DebitNote debitNote = new DebitNote() { DebitNoteNumber = "CN009", Amount = 77.77m };
TransactionLog debitNoteLog = new TransactionLog() { Amount = debitNote.Amount, DocumentTypeId = 3 };
debitNote.TransactionLog = debitNoteLog;
_context.DebitNotes.Add(debitNote);

Answer 3

我猜你的关系有问题。就像一笔交易可以有多张发票，但一张发票只有一个交易记录。我可能错了，因为有时感觉像是一对一的，但无论如何我试了一下，这就是你想要的。

实体：

public class TestMVCEntities : DbContext
{

    public TestMVCEntities()
        : base("name=TestMVCEntities")
    {
    }

    public DbSet<Invoice> Invoices { get; set; }
    public DbSet<DebitNote> DebitNotes { get; set; }
    public DbSet<CreditNote> CreditNotes { get; set; }
    public DbSet<TransactionLog> TransactionLogs { get; set; }


    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<TransactionLog>()
            .HasRequired(p => p.Invoice)
            .WithMany(p => p.InvoiceLog)
            .HasForeignKey(p => p.DocumentId);

        modelBuilder.Entity<TransactionLog>()
            .HasRequired(p => p.DebitNote)
            .WithMany(p => p.DebitLog)
            .HasForeignKey(p => p.DocumentId);

        modelBuilder.Entity<TransactionLog>()
            .HasRequired(p => p.CreditNote)
            .WithMany(p => p.CreditLog)
            .HasForeignKey(p => p.DocumentId);
    }
}

public partial class TransactionLog
{
    public int TransactionLogId { get; set; }
    public int? DocumentId { get; set; }
    public int? DocumentTypeId { get; set; }
    public decimal? Amount { get; set; }

    public CreditNote CreditNote { get; set; }
    public Invoice Invoice { get; set; }
    public DebitNote DebitNote { get; set; }
}

public partial class Invoice
{
    public int InvoiceId { get; set; }
    public string InvoiceNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> InvoiceLog { get; set; }
}

public partial class DebitNote
{
    public int DebitNoteId { get; set; }
    public string DebitNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> DebitLog { get; set; }
}

public partial class CreditNote
{
    public int CreditNoteId { get; set; }
    public string CreditNoteNumber { get; set; }
    public decimal Amount { get; set; }

    public ICollection<TransactionLog> CreditLog { get; set; }
}  

并插入数据：

var invoice = new Invoice()
    {
        InvoiceNumber = "Inv099",
        Amount = 66m,
        InvoiceLog = new Collection<TransactionLog>()
        {
            new TransactionLog(){DocumentTypeId = 1, Amount = 66m}
        }
    };

    var creditNote = new CreditNote()
    {
        CreditNoteNumber = "DN002",
        Amount = 99.99m,
        CreditLog = new Collection<TransactionLog>()
        {
            new TransactionLog(){DocumentTypeId = 3, Amount = 99.99m}
        }
    };

    var debitNote = new DebitNote()
    {
        DebitNoteNumber = "CN008",
        Amount = 77.77m,
        DebitLog = new Collection<TransactionLog>()
        {
            new TransactionLog(){DocumentTypeId = 2, Amount = 77.77m}
        }
    };

    using (var context = new TestMVCEntities())
    {
        context.Invoices.Add(invoice);
        context.CreditNotes.Add(creditNote);
        context.DebitNotes.Add(debitNote);
        context.SaveChanges();
    }  

表格将如下所示：